Dart in Action

426 Pages·2013·15.62 MB·English

by  Chris Buckett

Chris Buckett
F Seth Ladd
OREWORDBY
M A N N I N G
Dart in Action

Dart in Action
CHRIS BUCKETT
MANNING
Shelter Island
For online information and ordering of this and other Manning books, please visit
www.manning.com. The publisher offers discounts on this book when ordered in quantity.
For more information, please contact
Special Sales Department
Manning Publications Co.
20 Baldwin Road
PO Box 261
Shelter Island, NY 11964
Email: [email protected]
©2013 by Manning Publications Co. All rights reserved.
No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in
any form or by means electronic, mechanical, photocopying, or otherwise, without prior written
permission of the publisher.
Many of the designations used by manufacturers and sellers to distinguish their products are
claimed as trademarks. Where those designations appear in the book, and Manning
Publications was aware of a trademark claim, the designations have been printed in initial caps
or all caps.
Recognizing the importance of preserving what has been written, it is Manning’s policy to have
the books we publish printed on acid-free paper, and we exert our best efforts to that end.
Recognizing also our responsibility to conserve the resources of our planet, Manning books are
printed on paper that is at least 15 percent recycled and processed without the use of elemental
chlorine.
Development editor: Susanna Kline
Manning Publications Co. Technical proofreader: John Evans
20 Baldwin Road Copyeditor: Tiffany Taylor
PO Box 261 Proofreader: Toma Mulligan
Shelter Island, NY 11964 Typesetter: Gordan Salinovic
Cover designer: Marija Tudor
ISBN 9781617290862
Printed in the United States of America
1 2 3 4 5 6 7 8 9 10 – MAL – 17 16 15 14 13 12
brief contents
P 1 I D .........................................................1
ART NTRODUCING ART
1 ■ Hello Dart 3
2 ■ “Hello World” with Dart tools 24
3 ■ Building and testing your own Dart app 40
P 2 C D .................................................................. 69
ART ORE ART
4 ■ Functional first-class functions and closures 71
5 ■ Understanding libraries and privacy 94
6 ■ Constructing classes and interfaces 119
7 ■ Extending classes and interfaces 138
8 ■ Collections of richer classes 158
9 ■ Asynchronous programming with callbacks and futures 183
P 3 C - D .................................................209
ART LIENT SIDE ART APPS
10 ■ Building a Dart web app 211
11 ■ Navigating offline data 237
12 ■ Communicating with other systems and languages 258
v
vi BRIEF CONTENTS
P 4 S - D ........................................................281
ART ERVER SIDE ART
13 ■ Server interaction with files and HTTP 283
14 ■ Sending, syncing, and storing data 308
15 ■ Concurrency with isolates 331
contents
foreword xv
preface xvii
acknowledgments xix
about this book xxi
about the cover illustration xxv
P 1 I D .............................................1
ART NTRODUCING ART
1 Hello Dart 3
1.1 What is Dart? 3
A familiar syntax to help language adoption 5 ■ Single-page
application architecture 6
1.2 A look at the Dart language 7
String interpolation 7 ■ Optional types in action 9
Traditional class-based structure 10 ■ Implied interface
definitions 11 ■ Factory constructors to provide default
implementations 12 ■ Libraries and scope 13 ■ Functions
as first-class objects 16 ■ Concurrency with isolates 17
1.3 Web programming with Dart 18
dart:html: a cleaner DOM library for the browser 18 ■ Dart and
HTML5 19
vii
viii CONTENTS
1.4 The Dart tool ecosystem 20
The Dart Editor 20 ■ Dart virtual machine 21 ■ Dartium 21
dart2js: the Dart-to-JavaScript converter 22 ■ Pub for package
management 22
1.5 Summary 23
2 “Hello World” with Dart tools 24
2.1 The command-line Dart VM 25
2.2 “Hello World” with the Dart Editor 26
Exploring the Dart Editor tools 27 ■ The relationship between Dart
and HTML files 30 ■ Running “Hello World” with Dartium 30
Using dart2js to convert to JavaScript 32 ■ Generating
documentation with dartdoc 34 ■ Debugging Dart with
breakpoints 34
2.3 Importing libraries to update the browser UI 35
Importing Dart libraries 36 ■ Accessing DOM elements with
dart:html 37 ■ Dynamically adding new elements to the page 38
2.4 Summary 39
3 Building and testing your own Dart app 40
3.1 Building a UI with dart:html 41
Entry-point HTML 42 ■ Creating dart:html elements 42
Creating a new Element from HTML snippets 44 ■ Creating
elements by tag name 45 ■ Adding elements to an HTML
document 46
3.2 Building interactivity with browser events 49
Adding the PackList item from a button click 49 ■ Event handling
with Dart’s flexible function syntax 50 ■ Responding to dart:html
browser events 52 ■ Refactoring the event listener for reuse 53
Querying HTML elements in dart:html 54
3.3 Wrapping structure and functionality with classes 56
Dart classes are familiar 57 ■ Constructing the PackItem
class 57 ■ Wrapping functionality with property getters and
setters 59
3.4 Unit-testing the code 62
Creating unit tests 64 ■ Defining test expectations 64
Creating a custom matcher 66
3.5 Summary 67
CONTENTS ix
P 2 C D ......................................................69
ART ORE ART
4 Functional first-class functions and closures 71
4.1 Examining Dart functions 72
Function return types and the return keyword 74 ■ Providing
input with function parameters 77
4.2 Using first-class functions 82
Local function declarations 83 ■ Defining strong function
types 88
4.3 Closures 91
4.4 Summary 93
5 Understanding libraries and privacy 94
5.1 Defining and importing libraries in your code 95
Defining a library with the library keyword 96 ■ Importing
libraries with import 98
5.2 Hiding functionality with library privacy 103
Using privacy in classes 105 ■ Using private functions in
libraries 109
5.3 Organizing library source code 110
Using the part and part of keywords 111
5.4 Packaging your libraries 114
5.5 Scripts are runnable libraries 116
5.6 Summary 118
6 Constructing classes and interfaces 119
6.1 Defining a simple class 120
Coding against a class’s interface 121 ■ Formalizing interfaces
with explicit interface definitions 123 ■ Using multiple
interfaces 124 ■ Declaring property getters and setters 125
6.2 Constructing classes and interfaces 126
Constructing class instances 127 ■ Designing and using classes
with multiple constructors 128 ■ Using factory constructors to
create instances of abstract classes 129 ■ Reusing objects with
factory constructors 130 ■ Using static methods and properties
with factory constructors 132